| In order to study the construction control technology and remote unattended intelligent perception technology of long-span continuous rigid frame bridge,based on the second continuous rigid frame part of Hegou Bridge in Lingtai-Huating section of expressway S28 line,this paper studies and discusses the hydration heat crack resistance control of large volume bearing platform of rigid frame bridge,stress and linear control of superstructure,internal force,stress and deflection variation law of beam body under asymmetric load,establishment and application of remote intelligent perception system,so as to guide the supporting project and provide reference for similar projects.The main contents of this paper are as follows :(1)Midas FEA finite element software is used to simulate the monitored target cap.The accuracy of the model is verified by comparing the measured temperature field with the calculated temperature field.In this paper,the feasibility of early crack resistance of large-volume pile caps is studied from two aspects of water pipe diameter and inlet temperature.It is found that it is more reasonable when the water pipe diameter is set to 5 cm.The lower the inlet temperature is,the better the cooling effect is,but it should not be too low.The difference between the inlet water temperature and the maximum temperature inside the structure is less than 25 °C.It is suggested that the pipe cooling system should be closed after 2 ～ 3 days after the temperature of the pile cap drops,or when the difference between the maximum temperature and the ambient temperature is less than 15 ° C.Secondly,the thermal conductivity of its thermal parameters is selected as the research object.Considering the influence of the heat transfer characteristics of concrete on the temperature difference between the inner and outer surfaces of large volume caps,the results show that the larger the thermal conductivity is,the more obvious the temperature difference between the inner and outer surfaces of concrete is,and the better the crack resistance effect is.Finally,through the hydration heat experiment,the influence of different dosage of fly ash on cement hydration is studied,which shows that the incorporation of fly ash in mass concrete structure can effectively prevent early cracking.(2)Using Midas / Civil numerical simulation software to simulate the whole bridge of Hegou Bridge.Based on the engineering example,the variation law of bending moment,shear force,stress and deflection at the key section of the beam body under asymmetric load is discussed.The results show that under the research background of this paper,the influence of asymmetric load on the deflection of the bridge is great.When the asymmetric load is applied to the maximum cantilever end,the maximum deflection can reach 10 mm,and the non-forced side deflection is6～7 mm.(3)Based on the Hegou Bridge,the overall design of the bridge intelligent sensing monitoring system is carried out.The system mainly includes sensor system,data acquisition and transmission system,remote monitoring platform and intelligent early warning system.By embedding two sets of sensors in parallel at the same position at the root of the 0 # block,and comparing the intelligent acquisition stress data with the conventional detection data,the accuracy of the system ’s stress intelligent monitoring data is verified to meet the construction monitoring accuracy requirements.Through the integration of ’ measured data + simulated data ’,the stress state of the whole bridge is intelligently perceived,and the measured stress and calculated stress errors of different control sections during the construction of each section are monitored.The construction quality of each section is intelligently perceived,and the determination of the reasonable range of stress is discussed.The intelligent sensing monitoring of the bridge during the construction stage is carried out by using the method of multi-section and double index.(4)The content and goal of the bridge construction monitoring are expounded.The temperature field of the bridge cap is monitored by using the remote unmanned intelligent sensing system,and the temperature field law of the mass concrete structure is obtained.The key parts of 3 # pier and 4 # pier beam body(0 # block root,side span 1/4,1/2,3/4 and middle span 1/8,1/4,3/8)are embedded with steel bar stress sensors.Through the unmanned monitoring system,the stress state of the beam body is monitored in real time,and the stress variation law of the beam body in the construction stage of the continuous rigid frame bridge is analyzed to ensure the reasonable stress of the box girder.The bridge linearity is monitored,and the measured elevation and the ideal formwork elevation are compared,indicating that the bridge linearity monitoring is good. |
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